MAR Chart Codes: Complete Care Home Reference

This guide explains MAR chart coding conventions for care homes in England. Codes vary slightly between dispensing pharmacies, so always use the key printed on your own MAR charts as the definitive reference. This is general guidance on record-keeping, not clinical advice — for decisions about specific medicines, including controlled drugs and covert administration, follow your dispensing pharmacy's instructions and your local medicines optimisation team. References to NICE guidance and legislation are current as of the last reviewed date above.

A MAR chart code is a single letter or short abbreviation a care worker writes in a dose slot to explain why a medicine was not signed as given. The codes are not standardised across England, but the common ones — R for refused, H for in hospital, D for destroyed or discontinued, S for self-administered — appear on almost every chart. The one rule that matters more than the codes themselves: a blank dose slot is treated as a medication error, so every slot must carry either a signature or a code.

If you manage medicines in a care home, you already know that the Care Quality Commission (CQC) reviews a sample of MAR charts at every inspection. What trips homes up is rarely a misunderstood code. It is gaps, illegible entries, and codes used inconsistently between staff. This guide lists the codes you will meet, explains what each one means, and shows where CQC actually looks.

What a MAR chart is, and why coding matters

A Medication Administration Record (MAR) chart is the primary evidence that a resident received the medicines prescribed for them. It records the medicine, the dose, the time, and a signature for every administration — or a code for every non-administration.

The legal basis sits in two places. Regulation 12(2)(g) of the Health and Social Care Act 2008 (Regulated Activities) Regulations 2014 requires "the proper and safe management of medicines." And Regulation 17(2)(c) requires you to "maintain securely an accurate, complete and contemporaneous record in respect of each service user, including a record of the care and treatment provided." A MAR chart with unexplained gaps fails both — it is neither complete nor an accurate record of what happened.

The practice standard comes from NICE guideline SC1 (Managing medicines in care homes), which CQC assessors reference frequently. SC1 sets the expectation that records are accurate, up to date, and clear enough that any member of staff can see at a glance what was given and what was not.

That is why coding matters. The code is how you turn a blank space — which looks like a missed dose — into a documented, defensible decision.

The common MAR chart codes

These are the codes you will see most often. The exact letters depend on your pharmacy's template, so check your own key first, but the meanings are consistent.

Code	Meaning	When to use it
(signature/initials)	Administered	The medicine was given. Sign or initial the slot.
R	Refused	The resident declined the medicine. Record the refusal and, where relevant, follow up (repeated refusals need escalation).
NT or N	Not taken / not available	The resident was not available at the round (asleep, out, at an appointment) and the dose was not given.
H	In hospital	The resident was in hospital and the medicine was managed there.
D	Destroyed / discontinued	The medicine was stopped by the prescriber, or returned and destroyed. Cross-reference the prescriber's instruction.
S	Self-administered	The resident manages this medicine themselves following a risk assessment. The slot is signed by the resident or marked per your self-administration policy.
L	Leave / social leave	The resident was away from the home (e.g. visiting family) and took the medicine with them.
O	Other / see notes	None of the standard codes fit — a written explanation must appear in the daily notes or on the reverse of the chart.
P	PRN given	Used on some charts to flag that a "when required" medicine was administered, with the reason recorded separately.

A few codes carry extra weight:

• R (refused) is not a neutral mark. One refusal is recorded and moved on from. A pattern of refusals — the same medicine refused repeatedly — is a clinical signal that needs raising with the GP or pharmacist, because the resident may be experiencing side effects, swallowing difficulties, or a change in capacity. CQC looks for evidence that you acted on patterns, not just logged them.
• D (destroyed/discontinued) must always tie back to a prescriber's instruction. A medicine should never be marked discontinued on a care worker's judgement alone.
• NT (not taken) needs a reason in the notes. "Resident asleep at 8am round, dose given at 10am" is fine. A bare NT with no explanation reads to an inspector as a gap with a letter in it.

PRN medicines need more than a code

"When required" (PRN) medicines — pain relief, anxiety medication, laxatives taken only when needed — are where MAR coding most often falls down. A code alone is never enough for a PRN dose.

Every PRN medicine should have a written PRN protocol stating:

• The indication (what the medicine is for)
• The dose and the dose range
• The maximum frequency and maximum daily dose
• What to assess before giving it, and what to monitor afterwards

When a PRN dose is given, the MAR slot is signed and the reason is recorded — "given at 14:30 for hip pain reported by resident, settled by 15:15." Without the protocol and the reason, different staff give the same medicine for different reasons at different thresholds, which is exactly the inconsistency CQC flags. This connects closely to the broader medicines requirements covered in our guide to medication management in care homes.

How to correct a MAR chart error

Staff make mistakes — a slot signed in the wrong row, a code entered against the wrong medicine. The way you correct it is itself an audit point.

• Never use correction fluid or scribble an entry out so it cannot be read.
• Draw a single line through the error so the original remains legible.
• Date and initial the correction.
• Add a brief note explaining the change if it is not self-evident.

The principle is the same one that governs controlled drugs registers: the record must show its own history. An entry that has been obliterated looks like something is being hidden, even when nothing is.

What CQC checks on MAR charts

When an assessor reviews a sample of MAR charts, they are looking for a small number of things. Knowing them lets you audit your own charts the way an inspector would.

1. No unexplained gaps. Every dose slot is signed or coded. This is among the most consistently cited medication findings in published inspection reports, and it almost always cites Regulation 12.
2. Codes are used consistently. The same situation produces the same code across staff and shifts. A key is printed on the chart so codes are not improvised.
3. Allergies are documented. Including "NKDA" (no known drug allergies) written explicitly, not just left blank.
4. PRN protocols exist for every "when required" medicine, and PRN doses carry a recorded reason.
5. Handwritten entries are countersigned. Where a medicine is handwritten onto a chart mid-cycle, two staff sign it and the prescriber or pharmacist countersigns at the earliest opportunity.
6. Corrections are legible. Single line, dated, initialled — never blanked out.

For a structured way to check these on a monthly cycle rather than discovering problems at inspection, see our guide on running a care home audit, and our walkthrough of building a full care home audit schedule that includes a recurring MAR chart review.

A quick self-audit you can run this week

If you want to know where you stand before CQC tells you, run this on a sample of charts (10–20%, or all of them if you have fewer than 20 residents):

1. Take last month's charts and scan every dose slot. Count the blanks. Your target for unexplained gaps is zero.
2. For every code used, check there is a corresponding note where the code requires one (NT, O, D, and every PRN dose).
3. Check each PRN medicine has a current written protocol.
4. Confirm allergy status is recorded on every chart, including NKDA.
5. Look at your refusals. Is any medicine being refused repeatedly with no evidence of escalation?

The gaps you find are the findings an inspector would have written up. Fixing them now is a great deal cheaper than fixing them after a Regulation 12 breach.

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